Re: [PATCH 1/4] of: Add support for linking device tree blobs into vmlinux
From: Michal Marek <hidden>
Date: 2010-12-22 22:36:38
Also in:
linux-arch, linux-devicetree, linux-kbuild, lkml
On 22.12.2010 20:57, dirk.brandewie@gmail.com wrote:
From: Dirk Brandewie<redacted>
This patch adds support for linking device tree blob(s) into
vmlinux. Modifies asm-generic/vmlinux.lds.h to add linking
.dtb sections into vmlinux. To maintain compatiblity with the of/fdt
driver code platforms MUST copy the blob to a non-init memory location
before the kernel frees the .init.* sections in the image.
Modifies scripts/Makefile.lib to add a kbuild command to
compile DTS files to device tree blobs and a rule to create objects to
wrap the blobs for linking.
STRUCT_ALIGNMENT is defined in vmlinux.lds.h for use in the rule to
create wrapper objects for the dtb in Makefile.lib. The
STRUCT_ALIGN() macro in vmlinux.lds.h is modified to use the
STRUCT_ALIGNMENT definition.
The DTB's are placed on 32 byte boundries to allow parsing the blob
with driver/of/fdt.c during early boot without having to copy the blob
to get the structure alignment GCC expects.
A DTB is linked in by adding the DTB object to the list of objects to
be linked into vmlinux in the archtecture specific Makefile using
obj-y += foo.dtb.o
Signed-off-by: Dirk Brandewie<redacted>Hi, you can add Acked-by: Michal Marek <redacted> but I thing this series should go through the tip tree, as your primary target seems to be x86 and patch 2/4 depends on the ce4100 code that is only in tip. Michal
quoted hunk ↗ jump to hunk
--- Documentation/kbuild/makefiles.txt | 15 +++++++++++++++ include/asm-generic/vmlinux.lds.h | 13 +++++++++++-- scripts/Makefile.lib | 23 +++++++++++++++++++++++ 3 files changed, 49 insertions(+), 2 deletions(-)diff --git a/Documentation/kbuild/makefiles.txt b/Documentation/kbuild/makefiles.txt index 0ef00bd..86e3cd0 100644 --- a/Documentation/kbuild/makefiles.txt +++ b/Documentation/kbuild/makefiles.txt@@ -1136,6 +1136,21 @@ When kbuild executes, the following steps are followed (roughly): resulting in the target file being recompiled for no obvious reason. + dtc + Create flattend device tree blob object suitable for linking + into vmlinux. Device tree blobs linked into vmlinux are placed + in an init section in the image. Platform code *must* copy the + blob to non-init memory prior to calling unflatten_device_tree(). + + Example: + #arch/x86/platform/ce4100/Makefile + clean-files := *dtb.S + + DTC_FLAGS := -p 1024 + obj-y += foo.dtb.o + + $(obj)/%.dtb: $(src)/%.dts + $(call cmd,dtc) --- 6.7 Custom kbuild commandsdiff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h index bd69d79..05cbad0 100644 --- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h@@ -67,7 +67,8 @@ * Align to a 32 byte boundary equal to the * alignment gcc 4.5 uses for a struct */ -#define STRUCT_ALIGN() . = ALIGN(32) +#define STRUCT_ALIGNMENT 32 +#define STRUCT_ALIGN() . = ALIGN(STRUCT_ALIGNMENT) /* The actual configuration determine if the init/exit sections * are handled as text/data or they can be discarded (which@@ -146,6 +147,13 @@ #define TRACE_SYSCALLS() #endif + +#define KERNEL_DTB() \ + STRUCT_ALIGN(); \ + VMLINUX_SYMBOL(__dtb_start) = .; \ + *(.dtb.init.rodata) \ + VMLINUX_SYMBOL(__dtb_end) = .; + /* .data section */ #define DATA_DATA \ *(.data) \@@ -468,7 +476,8 @@ MCOUNT_REC() \ DEV_DISCARD(init.rodata) \ CPU_DISCARD(init.rodata) \ - MEM_DISCARD(init.rodata) + MEM_DISCARD(init.rodata) \ + KERNEL_DTB() #define INIT_TEXT \ *(.init.text) \diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib index 4c72c11..7df8eb5 100644 --- a/scripts/Makefile.lib +++ b/scripts/Makefile.lib@@ -200,6 +200,29 @@ quiet_cmd_gzip = GZIP $@ cmd_gzip = (cat $(filter-out FORCE,$^) | gzip -f -9> $@) || \ (rm -f $@ ; false) +# DTC +# --------------------------------------------------------------------------- + +# Generate an assembly file to wrap the output of the device tree compiler +quiet_cmd_dt_S_dtb= DTB $@ +cmd_dt_S_dtb= \ +( \ + echo '\#include<asm-generic/vmlinux.lds.h>'; \ + echo '.section .dtb.init.rodata,"a"'; \ + echo '.balign STRUCT_ALIGNMENT'; \ + echo '.global __dtb_$(*F)_begin'; \ + echo '__dtb_$(*F)_begin:'; \ + echo '.incbin "$<" '; \ + echo '__dtb_$(*F)_end:'; \ + echo '.global __dtb_$(*F)_end'; \ + echo '.balign STRUCT_ALIGNMENT'; \ +)> $@ + +$(obj)/%.dtb.S: $(obj)/%.dtb + $(call cmd,dt_S_dtb) + +quiet_cmd_dtc = DTC $@ + cmd_dtc = $(objtree)/scripts/dtc/dtc -O dtb -o $@ -b 0 $(DTC_FLAGS) $< # Bzip2 # ---------------------------------------------------------------------------